.MAKEFLAGS edited is not taken into account e.g. in make.conf

[Mathieu Prevot]

Hello,

only real arguments (passed with command) are taken into account,
when I edit .MAKEFLAGS (makefile or /etc/make.conf) there is a new .MAKEFLAGS
but there no expected effects.
You can test this with the -dA option, and with the following ./makefile
content (extract):
-----
.MAKEFLAGS+= -dA
disp:
	@echo ${.MAKEFLAGS}
-----

`make -dA` works fine
`make -dA disp` displays "-dA -dA"

BUT

`make` does NOT work i.e. there is no debug output
`make disp` displays "-dA"

I use RELENG_6 amd64 ...

regards,
Mathieu